I had replaced an alternator because I had battery light on the dash. Problem fixed, but no instead of a red light now have amber Check Engine light. Bad alternator ran down battery, disconnected it and recharged for several hours.

Apparently that is why CEL is on. Had the guys at Autozone reset it with some gadget twice which helped for about 10 minutes. Now CEL back on. Was told to take off gas cap. Didn’t help. Am told problem should clear up on its own after a while and nothing wrong with engine, but still uncomfortable with the amber irritater. Any ideas?

The reason the Check Engine light is on is, when you disconnect the battery, or if a battery goes dead, the monitors for the OBDII systems are lost. To reset the monitors for the OBDII system the vehicle has to be driven under certain conditions. This is called the Drive Cycle.

Tester, If You Get A Minute, Could You Give Me A Quick “Drive Cycles 101” Lecture?

I’ve disconnected lots of batteries and have never had to run a “drive cycle”. I can’t find them in my Factory Service Manuals. Why can’t I find it?

Have I been putting the cars through it just by normal driving?
How long does one have to perform it before the CEL comes on?
How long will the CEL illuminate after the drive cycle completes?
Are there other common names for “drive cycle”? ECM relearning, etcetera?

Interesting link Tester, thanks. I ran into a problem like this when my battery died before getting my IM test. The tech had a book that showed what needed to be done in order to get the tests started. It was a number of things I had to do while driving and stopping.

Only one code came up…P0443. Guy cleared his scanner. CEL is gone, but this has happened twice before. He said he thought it was the gas cap. I had wiped the cap previously making sure there wasn’t anything on the rubber-like ring around the cap. But the CEL came back again. We’ll see what the morrow brings.